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Register a new userObservation of the $varLambda^0_b to varLambda^+_c K^+ K^- pi^-$ decay
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The $varLambda^0_b to varLambda^+_c K^+ K^- pi^-$ decay is observed for the first time using a data sample of proton-proton collisions at centre-of-mass energies of $sqrt{s}=7$ and 8 $rm{TeV}$ collected by the $mbox{LHCb}$ detector, corresponding to an integrated luminosity of $3{rm{fb}^{-1}}$. The ratio of branching fractions between the $varLambda^0_b to varLambda^+_c K^+ K^- pi^-$ and the $varLambda^{0}_{b}tovarLambda^{+}_{c}D^{-}_{s}$ decays is measured to be begin{equation*} frac{mathcal{B} ( varLambda^0_b to varLambda^+_c K^+ K^- pi^-) } {mathcal{B} ( varLambda^0_b to varLambda^+_c D^-_s)} = (9.26 pm 0.29 pm 0.46 pm 0.26)times10^{-2}, end{equation*} where the first uncertainty is statistical, the second systematic and the third is due to the knowledge of the $D^-_s to K^+ K^- pi^-$ branching fraction. No structure on the invariant mass distribution of the $varLambda^+_c K^+$ system is found, consistent with no open-charm pentaquark signature.
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The $B^+ to D^{*-}K^+pi^+$ decay potentially provides an excellent way to investigate charm meson spectroscopy. The decay is searched for in a sample of proton-proton collision data collected with the LHCb detector at centre-of-mass energies of 7 and 8 TeV, corresponding to an integrated luminosity of $3~{rm fb}^{-1}$. A clear signal is observed, and the ratio of its branching fraction to that of the $B^+ to D^{*-}pi^+pi^+$ normalisation channel is measured to be begin{equation*} frac{mathcal{B}(B^+ to D^{*-}K^+pi^+)}{mathcal{B}(B^+ to D^{*-}pi^+pi^+)} = left( 6.39 pm 0.27 pm 0.48 right) times 10^{-2} , , end{equation*} where the first uncertainty is statistical and the second is systematic. This is the first observation of the $B^+ to D^{*-}K^+pi^+$ decay.
We report the first observation of the doubly Cabibbo-suppressed decay $D^+_sto K^+K^+pi^-$ using 605 fb$^{-1}$ of data collected with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. The branching ratio with respect to its Cabibbo-favored counterpart $mathcal{B}(D^+_sto K^+K^+pi^-)$ / $mathcal{B}(D^+_sto K^+K^-pi^+)$ is (0.229$pm0.028pm$0.012)%, where the first uncertainty is statistical and the second is systematic. We also report a significantly improved measurement of the doubly Cabibbo-suppressed decay $D^+to K^+pi^+pi^-$, with a branching ratio $mathcal{B}(D^+to K^+pi^+pi^-)$ / $mathcal{B}(D^+to K^-pi^+pi^+)$=(0.569$pm0.018pm$0.014)%.
The decay $B_crightarrow J/psi K^+ K^- pi^+$ is observed for the first time, using proton-proton collisions collected with the LHCb detector corresponding to an integrated luminosity of 3fb$^{-1}$. A signal yield of $78pm14$ decays is reported with a significance of 6.2 standard deviations. The ratio of the branching fraction of $B_c rightarrow J/psi K^+ K^- pi^+$ decays to that of $B_c rightarrow J/psi pi^+$ decays is measured to be $0.53pm 0.10pm0.05$, where the first uncertainty is statistical and the second is systematic.
The first observation of the decay K^+ --> pi^+ gamma gamma is reported. A total of 31 events was observed with an estimated background of 5.1 +- 3.3 events in the pi+ momentum range from 100 MeV/c to 180 MeV/c. The corresponding partial branching ratio, B(K+ -> pi+ gamma gamma, 100 MeV/c < P_pi^+ < 180 MeV/c), is (6.0 +- 1.5 (stat) +- 0.7 (sys)) x 10^{-7}. No K^+ --> pi^+ gamma gamma decay was observed in the pi^+ momentum region greater than 215 MeV/c. The observed pi^+ momentum spectrum is compared with the predictions of chiral perturbation theory.
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